A competitive inhibitor of renal renin based on the amino acid sequence of natural substrate has been synthesized. The peptide Pro-His-Pro-Phe-His-Phe-Phe-Val-Tyr-Lys contains modifications at the N-terminus to increase solubility and make the peptide specific for primate renin. Modifications at the cleavage site increase binding to renin and addition of a lysyl residue to the C-terminus increase solubility and extends half-life in vivo. The peptide specifically blocks the action of exogenous renin but does not affect equivalent pressure rises induced by either angiotensins I or II. In the salt depleted monkey bolus injections of the peptide decrease pressure substantially and about as effectively as teprotide.